Helper T-Cells Maintain Immune Protection Against HCV

A recent study describes the interaction of CD4+ ("helper”) and CD8+ ("killer”) T lymphocytes during the immune response that develops when an individual is infected by the hepatitis C virus (HCV).

HCV causes liver damage in about 170 million people around the world. To learn how the body defends itself against the virus, investigators at Ohio State University (Columbus, USA) used chimpanzees to study the effect of depleting certain lymphocyte populations from the immune system. They reported in the October 24, 2003, issue of Science that chimpanzees which had become immune to HCV after recovering from the disease lost their immunity when CD4+ lymphocytes were removed by antibody treatment. The virus was able to avoid the CD8+ cells that remained and establish a new infection.

"Our goal is to understand how a person's immune response determines the outcome of the hepatitis C infection,” explained senior author Dr. Christopher M. Walker, professor of pediatrics at the Ohio State University College of Medicine and Public Health. "Approximately 70% of individuals exposed to hepatitis C become lifelong carriers of the virus. The remaining individuals successfully contain the infection and appear to have long-lasting immunity to the virus. Our finding that CD4+ T helper cells are essential for this protection move us one step closer to developing an effective vaccine for hepatitis C.”




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